Hydraulic push rod for stretch draw press



ed Dec 5 I [/6 6 ets-s II jill q I I i J iil l -lll /1 I l p l [u h ll1' I 1| [I h I JIM I. ll j Y a April 16, 1968 s. M. DOLNEY HYDRAULICPUSH ROD FOR STRETCH DRAW PRESS 6 Sheets-Sheet 2 Filed Dec. 30, 1965 IINVENTOR.

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April 16, 1968 s. M. DOLNEY HYDRAULIC PUSH ROD FOR STRETCH DRAW PRESS 6Sheets-Sheet 15 Filed Dec. 30, 1965 INVENTOR.

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April 6, 1968 s. M. DOLNEY 3,377,335

HYDRAULIC PUSH ROD FOR STRETCH DRAW PRES Filed Dec. 30, 1965 6Sheets-Sheet 4 as F774. B 733M41 Ct 3- ATTORNEY.

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April 16, 1968 s. M. DOLNEY 3,377,835

HYDRAULIC PUSH ROD FOR STRETCH DRAW PRESS Filed Dec. 50, 1965 eSheets-Sheet 5 6 ATTORNEY.

April 16, 1968 s. M. DOLNEY 3,377,835

HYDRAULIC PUSH ROD FOR STRETCH DRAW PRESS Filed Dec. 30, 1965 sSheets-Sheet ATTORNEY.

United States Patent Filed Dec. 30, 1965, Ser. No. 517,616 8 Claims.(Cl. 72-305) This invention relates to stretch draw presses of thegeneral type disclosed in Us. Patent of Paul F. Maize, No. 3,113,607,issued Dec. 10, 1963, and entitled, Prestretch Forming Fixture ForDrawing Die Press.

In the above patent stretch units are arranged in a conventional drawingpress at opposite sides of the die space. These units were provided withgripping heads which grip two opposite margins of a strip of stock andhold it under tension while it is drawn by companion drawing dies. Theheads are supported on carriages which, in turn, are supported onvertically movable elevators. The heads can be moved relative to theirrespective elevators toward and away from the die space and theelevators can be moved vertically, during the concurrent stretching anddrawing operation.

In the above prior structure the elevators are moved upwardly anddownwardly by upright push rods mounted on the ram of the press. Theserods are arranged so as to engage the tops of the elevators, after theram has descended part way, and force them downwardly in fixed relationto the continued lowering of the ram. These push rods generally aremanually extensible and contractible endwise. However, the rods strikethe elevators with a severe impact and require very precise adjustmentfor proper operation.

In accordance with the present invention, push rod assemblages areprovided which are continuously connected to both the ram and elevatorsand efiect lowering and raising of the elevators without the severeimpact. The rod assemblages are such that precise adjustment of themaxially, parallel to the ram and elevator paths, is unnecessary forproper operation and protection of the equipment. Also, the rodassemblages are so connected to the elevators so as to provide acushioning effect when they become operative for lowering and returningthe elevators.

Various specific objects and advantages of the present invention willbecome apparent from the following description wherein reference is madeto the drawings, in which:

FIG. 1 is a front elevation of the stretch draw press embodying theprinciples of the present invention;

FIG. 2 is a right side elevation of the press illustrated in FIG. 1 andshowing a hydraulic circuit employed in connection therewith.

FIG. 3 is an enlarged fragmentary front elevation of a portion of thepress showing in greater detail one of the stretch draw units;

FIG. 4 is a top plan view of one of the stretch draw units and a portionof the press, illustrated in FIG. 3, part thereof being broken away forclearness in illustration;

FIG. 5 is a vertical sectional view of the stretch draw unit illustratedin FIG. 4 and is taken on the line 5-5 thereof.

FIG. 6 is a diagrammatic illustration of the stretch draw press of FIGS.1-4, showing the driving hydraulic circuitry therefor.

Referring to the drawings the press comp-rises a frame 1 includingupright corner posts 2, and a bolster block or bed 3. Mounted forvertical reciprocation on the upright corner posts 2 is a ram 4. The rammay be reciprocated vertically by any suitable means. In the formillustrated,

this means is shown as piston and cylinder assemblages 5 mounted on thetop of the frame. Each assemblage 5 includes cylinders 6 having a piston7 therein with its rod 7a connected to the top of the ram.

For die drawing the stock between companion drawing dies, a stationeryfem-ale die D1 is mounted on the ram and a companion male die D2 ismounted on suitable supports 8 resting on the bolster block 3.

Mounted on the bolster 3, one at each end of the die D2, are stretchforming units 9. The units 9 are preferably identical and generally suchas shown in US. Patent No. 3,116,780, of Cyril J. Bath, issued Jan. 7,1964.

As illustrated in the drawing, each unit 9 comprises upright side frames10 connected together by suitable transverse plates. An elevator 11 ismounted between each pair of side frame members for guided reciprocationin a vertical path, as more fully described in the above Bath patent.

Mounted on each elevator 11 is a tensioning unit which comprisesgenerally a carriage 12 on which is secured a suitable gripping head 13.Each head includes a stationery gripping jaw 13a fixed securely on thecarriage and a movable gripping jaw 13b pivoted to the carriage forrocking about a horizontal axis. The movable jaw is moved to and fromopen and closed position by a plurality of piston and cylinderassemblages 14. Each assemblage 14 includes a cylinder 15 having atransverse pivot 16, and a piston 17 having a rod 18. The pivot 16 ofeach cylinder provides a common pivot of two pivotally connected links19 and 20, respectively. The piston rod 18 is pivotally connected to thestationery jaw or to the carriage by means of a pivot 21. Thus, thecylinder 14 floats with the links 19 and 20 as they rock about the axisof the pivot 16. The outer end of the link 19 is pivotally connected tothe jaw 13b and the outer end of the link 20 is pivotally connected tothe carriage 12.

On top of the elevator 11 is a horizontal trackway 22. The carriage isprovided with a series of rollers 23 which ride on the trackway 22 sothat the carriage can move horizontally relative to the elevator towardand away from the die space.

In order to apply yieldable tensioning force to the heads 13, a bank oflike tensioning piston and cylinder assemblages 25 is provided. In theform illustrated, each assemblage of each bank comprises the cylinder 26having a piston 27 with a piston rod 28 extending therefrom. The rodsare pivotally connected by pivots 29 to suitable links 30. Each link 30is connected at one of its ends to theelevator 11 by means of a pivot31, and at its opposite end to the carriage 12 by means of a pivot 32.Each of the cylinders is mounted on its elevator 11 by means oftrunnions 33 so that the cylinders can rock about a common horizontalaxis and compensate for differences in elevation of pivot 29 andconsequent upon rocking of the link 30.

By admission of pressure fluid to the head ends of the cylinders 26,yieldable tension is applied to the stock through the medium of thelinks 30, carriages 12, and heads 13 in all positions of the elevators.

The specific structure of the stretching units as thus far described ismore fully shown and described in the above identified Patent No.3,116,780 of Cyril J. Bath.

As mentioned, in the Maize patent the push rods are mounted on the ramof the press and are arranged to engage the elevators after the ram hasmoved partway downwardly and thereupon move the elevators downwardly. Inthe present instance, instead of the push rods described in Maize, adifferent type of push rod assemblies is pro vided for driving theelevators by the ram. These push rod assemblies comprise the improvementof the present invention.

In the improved form of structure brackets 36 are fixedly mounted on theopposite ends of the elevators, respectively. Mounted fixedly in uprightposition on each bracket for movement vertically therewith is an uprightcylinder 37. Mounted in upright position on the ram are dependent pushrods 38 which are in the form of piston rods arranged one for eachcylinder 37. Each rod has at its lower end a piston 39 reciprocable inits associated cylinder 37. Each of the cylinders 37 is connected in ahydraulic circuit such that pressure fluid can be drawn into the headend of the cylinder freely, and discharged therefrom through a pressurerelief or control valve. For convenience, both cylinders 37 of the samestretch unit 9 are connected in parallel to such a valve, thoughobviously each might have its own circuit.

As best illustrated in FIG. 2, the head end of the cylinders areconnected by a conduit 40. A conduit 41 leads from the conduit 40 to anadjustable pressure relief valve 42' which can be adjusted forcontrolling the pressure developed in the head ends of the cylinders 37due to downward movement of the rods 38 and pistons 39 by the ram. Eachpressure control valve is set to release at a preselected maximumpressure.

The pressure control valve, in turn, discharges to a suitable sump 43. Aconduit 44 connects a check valve 45 in parallel with the valve 42. Thecheck valve 45 is arranged to open to permit free flow of the fluid fromthe sump into the head end of the associated cylinders 37 so that as thepistons 39 are lifted by rising of the ram, hydraulic fluid is drawninto the head ends of the cylinders, and to close to constrain the fluidto pass from the head ends of the cylinders 37 through the valve 42 upondownward movement of the pistons 39 by the ram.

A similar arrangement is used at the rod ends of the cylinders 37 if itis desired to dampen or cushion the application of lifting or returnforce to the elevators for lifting the elevators by the rods 38. Forthis latter purpose, a conduit 47 connects the rod ends of the cylinders36 in parallel. A conduit 48 leads from the conduit 47 to the adjustablepressure relief valve 49, similar to the valve 42, the pressure valvehaving its discharge connected to the sump 43. A line 50 connects acheck valve 51 in by-passing relation to the valve 49. The check valve51 is arranged to open so as to permit free flow of fiuid from the sumpto the rod end of the cylinders during lowering of the pistons 39 bydownward movement of the ram to force the pressure fluid in the rod endsof the cylinders to pass to the valve 49 upon lifting of the pistons 39by the ram. 7

When the ram begins lowering it does not instantly initiate the downwardtravel of the elevator as it would were solid or rigid push rodsprovided. Generally it is desired to lower the ram part way andgradually build up pressure in the head ends of the cylinders 37 torender the rods effective for driving the elevator. The inherentyieldability in the fittings and conduits of the hydraulic circuit areadequate to reduce the shock to a negligible amount.

The valve 42 may be set so that downward pressure built up in the headends of the cylinders 37 by the pistons upon lowering of the ram soonbecomes suflicient to force the elevator downwardly against theresistance of metal being stretched and drawn, whereupon the ram and theelevator lower together because of the hydraulic locking of the pistons39 and cylinders 37 in the downward direction. Thus the shock absorbingeffect is provided before the downward starting of the elevator.

The force at which a particular elevator is to be moved downwardly canreadily be determined for a given operation and the relief valve 42 ofthat elevator is set so that when such force is exceeded, the valveopens sufliciently to prevent further increase. It is to be noted thateach elevator has its own circuit and valves 42 and 49, so that each canbe separately controlled. Downward movement of an elevator can bearrested by closure of the dies or bottoming of the elevator in itssupporting frame, or by placing stop blocks 52 disposed between theframe of an elevator and the associated elevator. These blocks may bearranged in sets of difierent selected heights, the set used dependingupon the lowered position in which downward movement of a particularelevator is to be arrested. The valve necessarily opens, relieves thepressure, and thereby protects the equipment when downward movement ofthe elevator is arrested.

For the purposes of illustration, the units and ram are shown ascontrolled manually by circuitry, including remote control valves asillustrated in FIG. 6.

The circuitry for operating each stretch forming unit is separate from,but identical with, that of the other, and only one will be referred toin detail herein.

Each unit is supplied with hydraulic pressure fluid from a pump 56driven by a motor 57. The pump 56 is connected to a suitable controlvalve 59 which supplies pressure fluid to the stretch forming piston andcylinder assemblages 25. The valve 59 is arranged so that the flow ofhydraulic fluid to the ends of the assemblage can be reversed and theends opposite the pressure ends connected to a sump. When the valve 59is in an intermediate position the cylinders 25 are hydraulically lockedso that the associated unit can function merely as an anchorage, allstretching being performed by the opposite unit.

The pump 56 also supplies pressure fluid through the solenoid operatedvalve 61 to the cylinders 15 of the gripper jaw operating assemblages.

The fluid delivery to the piston and cylinder assemblages may beregulated by conventional remotely controlled hydraulic pressure andflow operators. For example, a settable pressure regulator 62, which maybe remotely controlled by a driving motor 63, is provided between thevalve 59 and the pressure side of the pump 56. A similar regulator 64,operated by remotely controlled motor 65, is interposed between thepressure side of the pump 56 and the valve 61.

The controls for the valves and regulators of both units are operablefrom a common panel.

As herein shown, the pressure fluid for operation of the ram is suppliedby a motor 67, having its pressure side connected to the assemblages 5by a conduit 68 through a remotely settable pressure control regulator69 and solenoid operated valve 70. The valve 70 can hydraulically lockthe assemblages 5 or supply pressure to the head ends of bothconcurrently for forcing the ram downwardly while venting the rod endsof the assemblages 5. The valve 70 may be set to reverse the flow ofhydraulic fluid for lifting the ram.

Necessarily the maximum pressure applied to the elevator by the ram uponmovement of the ram on its forming stroke is much greater than thatimposed on the elevator by the ram as the ram moves on its returnstroke. Accordingly, the valve 42 may be set at relatively high pressuredetermined by the pull-down force required for forming a particularpiece of metal. The valve 49, on the other hand, may be set atrelatively low pressure so as to assure lifting of the elevator andreturn of the piston 39. This pressure is dependent on the weight of theelevator and the parts supported thereon, and should be just enough tocause return of the elevator while not unduly resisting the return ofthe ram after the elevator has reached its return position and thepiston 39 is being returned relative to its cylinder.

For purposes of illustration herein, the cylinders 37 have been shown asconnected to the elevator bracket 36 and the push rods 38 connected tothe ram. However, if desired, these cylinders and push rods may bereversed, the cylinders being connected to the ram and the push rods tothe bracket of the elevator.

Having thus described my invention, I claim:

1. A stretch draw press comprising a bed having a die supporting space;

an upright frame;

a ram carried by the frame and movable in an upright path toward andaway from the bed in vertical alignment with the die space;

power means for driving the ram;

gripper means carried by the bed at one side of the die space;

a stretch forming unit on the bed at the other side of the die spaceincluding an elevator movable in a generally upright path, a carriage onthe elevator and movable relative thereto in a generally horizontalpath, stretch forming means for moving the carriage and for yieldablyresisting movement thereof, respectively, relative to the elevator alongsaid horizontal path, and a gripping head on and movable with thecarriage;

said heads being adapted to grip opposite margins, re-

spectively, of a sheet of metal for applying tension thereto;

power transmission means drivingly interconnecting the ram and elevatorfor driving the elevator downwardly by the ram;

characterized in that means are provided in the transmission means forlimiting to a preselected maximum the force transmittable by thetransmission means from the ram to the elevator on the forming stroke ofthe ram.

2. A stretch draw press according to claim 1 wherein the transmissionmeans includes a normally closed hydraulic circuit and the force istransmitted through the hydraulic fluid therein, and a pressure reliefvalve is connected in the circuit for releasing fluid therefrom when thepressure of the fluid in the circuit exceeds a predetermined maximum.

3. A stretch draw press according to claim 1 wherein additional meansare provided in the transmission means for limiting to a lowerpredetermined maximum the force transmitted by the transmission meansfrom the ram to the elevator on the return stroke of the ram.

4. A stretch draw press according to claim 1 wherein the transmissionmeans includes yieldable shock absorbing means which reduce shocksimposed on the elevator by the ram during movement of the ram on itsforming stroke.

5. A stretch draw press according to claim 1 wherein said powertransmission means are extensible and retractable push rods, each rodcomprising a piston and cylinder assemblage including a piston memberand a cylinder member, means connects one of the members to the ram formovement in a fixed relation thereto as the ram moves downwardly; meansconnecting the other member to the elevator for movement in fixedrelation thereto as the elevator moves downwardly;

pressure relief valve means are provided;

a hydraulic circuit connects one end of the cylinder member to the valvemeans so that the movement of the piston member relative to the cylindermember in one direction upon downward movement of the ram is resisted bythe fluid pressure which is dependent upon the pressure at which thevalve releases hydraulic pressure fluid from said one end of thecylinder; and

means are provided for admitting hydraulic fluid pressure to said oneend of the cylinder member upon relative movement of the members in theopposite direction.

6. A stretch draw press according to claim 5 wherein an additionalpressure relief valve means is provided, an additional hydraulic circuitconnects the other end of the cylinder member to the additional valvemeans so that movement of the piston member relative to the cylindermember in the said opposite direction is resisted by a preselectedpressure depending upon the pressure at which the additional valvereleases hydraulic pressure fluid from said other end, and additionalmeans are provided for admitting hydraulic fluid to said other end ofthe cylinder member upon relative movement of the members in said onedirection.

7. A stretch draw press according to claim 5 wherein the piston memberis connected fixedly in position on the ram, and the cylinder member isconnected fixedly in position on the elevator.

8. A stretch draw press according to claim 5 wherein said push rods areconnected to opposite sides of the elevator, respectively.

References Cited UNITED STATES PATENTS 1,315,937 9/1919 Artz 72305 X3,073,373 1/1963 Wheeler 72297 3,113,607 12/1963 Maize 72-296 3,116,7801/1964 Bath 72297 CHARLES W. LANHAM, Primary Examiner.

K. C. DECKER, Assistant Examiner.

1. A STRETCH DRAW PRESS COMPRISING A BED HAVING A DIE SUPPORTING SPACE;AN UPRIGHT FRAME; A RAM CARRIED BY THE FRAME AND MOVABLE IN AN UPRIGHTPATH TOWARD AND AWAY FROM THE BED IN VERTICAL ALIGNMENT WITH THE DIESPACE; POWER MEANS FOR DRIVING THE RAM; GRIPPER MEANS CARRIED BY THE BEDAT ONE SIDE OF THE DIE SPACE; A STRETCH FORMING UNIT ON THE BED AT THEOTHER SIDE OF THE DIE SPACE INCLUDING AN ELEVATOR MOVABLE IN A GENERALLYUPRIGHT PATH, A CARRIAGE ON THE ELEVATOR AND MOVABLE RELATIVE THERETO INA GENERALLY HORIZONTAL PATH, STRETCH FORMING MEANS FOR MOVING THECARRIAGE AND FOR YIELDABLY RESISTING MOVEMENT THERE-